Die-head for screw-cutting



F. MOUNTFORD AN-D R. STANDEN.

mE HEAD FOR scREw CUTTING.

1,394,107, Pfitented Oct. 18, 1921.

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. ranged the circumferential FREDERICK MOUNTFORD, OF NORTHFIELD, ND ROBERT STANDEN, 0F SMALL HEATH, BIRMINGHAM, ENGLAND.

DIE-HEAD FOR SCREW-CUTTIN G.

Application med July 7, 1919.

To @ZZ ywhom t may concern Be it known that we, FREDERICK MOUNT- ronn, of Yew Tree Farm, Northfield, Vorcestershire, England, manufacturer, and ROBERT STANDEN, of 33 Newland road, Green Lanes, Small Heath, Birmingham, England, have invented certain new and useful Improvements in and Relating to Die-Heads for Screw-Cutting, of which the following is a specification.

his invention comprises improvements in and relating to die heads/for screw cutting and has for its object to provide an automatically opening head of simple and compact construction, employing few parts.

It is known in die heads to arrange a die holder within a die head so that it may be moved axially with respect to the head against the action of a spring, and in this movement driving pins or pegs between the two parts are disengaged and the die holder is then rotated, by means of a circumferential spring or like means to open the dies by the cooperation of inclined slots and the pins or pegs aforesaid.

In some of these known constructions, the spring for drawing the die head and holder together has been arranged around a shank of the die holder usually near the end of the stem of the die head.

he main features of novelty7 in the combination embodying some of the above known features and forming our improved die head are:

l. The chambering of the die head and the arrangement of t e spring to draw the die holder` and head together in this chamber, the spigot part of the holder around which the spring is arranged being accommodated in this chamber.

2. The inclosing of the head in a cover or sleeve carried by the die holder which sleeve incloses a groove in the head in which is arspring for rotating the die holder to open the dies.

A further feature of the invention is the anchoring of the end of the circumferentially directed spring to the sleeve or cover attached to the die holder by a screw or pin in the cover having a plain end projecting inwardly to engage a loop in the end of the spring; while to allow the cover and die holder a limited axial and angular movement, an L or bayonet slot-like groove is Specification of Letters Patent.

Patented Oct. 18, 1921. Serial No. 309,113.

formed in the periphery of the head, and is engaged by a pin in the cover.-

Preferably two oppositely directed L- grooves are provided, so that in conjunction with the arrangement of the slots in the plate on the face of the head on each side holes in the head, the die head may be adapted to operate in either way to suit right or left hand screwing.

1r'llny means may be provided for automatica y tie pins of the die slides from the holes in the slots in the face plate.

For example an adjustable stop on the lathe may prevent the advance of the head which would cause the die holder to advance alone, and the automatic opening is effected y the circumferential spring pulling around the holder in the manner before set forth.

f desired the invention for die heads having more than two radial dies for screwing larger bodies.

In order that the invention may be more thoroughly understood and easily carried into practice, we have appended hereunto a sheet of explanatory drawings showing one example of the same.

Figure l is a sectional elevation.

Fig. 2 is an end elevation.

Fig. 8 is a cross section along line 3-3 of Fig. l.

F 4 is a cross section along line 4`4 of Fig. 3, showing the dies in working position.

tig. 5 is a similar view to Fig. 4 but showing the dies disengaged.

Fig. 6 is a cross section along line 6 6 of Fig. l.

Fig. 7 is a front view Fig. 8 is an elevation carriers.

The die heads comprise two main portions a and Z2. The stem c of portion b is adapted to slide within the head l of the portion a and has preferably a thin piece of tube d1 tted at of the die carriers. of one of the die said space. The head or face c of portion b is the die holder proper. The said die holder e is cut diametrically across with an undercut slot f, and into the slot f two slides or die carriers g and g are inserted radially. The said die carriers have secured in the rear around its stem7 face of each, a pin or peg h which projects from the back of the die carrier. The sleeve or stem part cof the die holder has acollar y' secured upon its inner en d, to bear against a spring k arranged around the said stem 0 in the chamber Z of the head d. T o the face of the head Z is secured a ring or plate m against the inner face of which the other end of the spring la bears. The die holder e is thus axially movable in the head dagainst the action of this spring la.

In the face of the plate orring m, are formed two slots n which communicate with two holes in the face of the head (Z. The slotsa inthe plate m extend on each side of the corresponding hole in the head, and are eccentric to the axis of the head.

When the head e of the die holder is in normal working position the pegs or pins h of the die slides on carriers g and g pass through the slots n, and are received in the holes 0 in the face of the head cl. The rear part of the head d has an annular peripheral groove 29, and a loop at one end of a tension spring Q is anchored by a pin 7" to the head e, and the l said spring is arranged in this groove p and has a loop in its other extremityl anchored to a sleeve or cover s by a pin or screw t. This sleeve or cover s is secured by handle u to the periphery of the die holder e and incloses the head. This spring is 'runder tension when the pins or pegs of the die slides are in the holes 0 of the head l and will pull the' die holder e rapidly around, if same is axially moved with respect to the head d, sufliciently to clear the pins h from the same holes 0. Such rotary movement of the holder ecarries the pins h up the eccentric slots fn.. and moves the die carriers radially outward, thus opening the dies o adjusted thereon by screws fw and secured by screws or pins y. 4The handle or thumb piece u is secured through the cover or sleeve s into the holder e for rotating it back to close the dies, and the die holder e is then drawn axially to the head Z by the spring 7c thus causing the pins 71, to enterthe holes 0 in the head d to lock the die carriers g and g in closed or working position. In order to yallow the sleeve or cover s and die holder e a limited axial andangular movement, an L or bayonet-slot-like groove is formed in the periphery of the head d, above the groove p, and is engaged by a pin y in the cover or sleeve s.

A bayonet slot -like groove similar to groove a: may be provided on the opposite side of the head CZ and inthe opposite direction for use when left hand screwing is done, and the spring g would be anchored by the same means the other way around, and the screwror pin y in sleeve s should be transferred to hole and slot e.

What we claim is l. Animproved die head for screw-cutting machines having a chamber at the front to accommodate a spigot or stem of the die holder, a spring in said chamber for arrangement around the spigot or stem for moving the holder axially and also having a circumferential groove in thel periphery, a circumferential spring arranged in said groove and adapted to rotate and open the dies when axial movement takes place between the die head and the die holder, and a cylindrical cover inclosng the parts of the said die holder and the said groove and circumferential spring.

2. An improved die head for screw-cutting machines having a chamber at the front to accommodate a spigot or stem of the die holder, a spring in said 'chamber for arrangement around the spigot or stem for moving the holder axially and also having a circumferential groove in the periphery, a circumferential spring arranged in said groove and adapted to rotate and open the dies when axial movement takes place between the die head and the die holder', a cylindrical cover inclosing the said groove and circumferential spring, a screw or pin in said cover to provide an anchorage forv one end ofthe said circumferential spring, and L orbayonet-slot-like.groove in theV periphery of the die head adapted to engage a pin in the said cover to allow a limited axial and rotary motion of the die holder.V

FREDERICK MONTFORD. Y ROBERT STANDEN. 

